The invention relates to a work machine, in particular in the form of a dump truck or truck, having a diesel electric drive, wherein a alternator is or can be driven by at least one internal combustion engine of the work machine.
Dump trucks or so-called large dump trucks are predominantly used in coal mining operations or ore mining operations for the transport of the mined coal, minerals and ores. These bulk material dumpers are manufactured in sizes of more than 90 metric tons (t) up to several 100 t in weight and payload so that they have very large dimensions overall.
A diesel electric drive is used as the traction drive, wherein the mechanical energy generated by this diesel engine is converted with the aid of a alternator into electrical energy for the supply of the electric traction drives. The reason for this process is that diesel engines, like all internal combustion engines, can only be operated with ideal efficiency in a very restricted speed range and cannot be started under load. The AC motors for the driving axle which are used can also produce the desired torque in the lower speed range for starting. The internal combustion engine used can be operated continuously in the ideal speed range. Corresponding work machines are described, for example, in DE 10 2014 003 374, DE 10 2014 003 203 and DE 10 2014 003 375.
In such work machines, a large number of components are at high voltage so that corresponding service or maintenance work for the service engineers is associated with great risks. The deployment of especially trained technical personnel is necessary due to this.
A possibility of safely carrying out corresponding service, maintenance and repair work is also switching off the diesel engine. This is, however, frequently not desired since the further systems which are driven by the diesel engine and which are not electrically operated, for example the hydraulic systems and the mechanically driven systems, are to continue to be available during the maintenance work on the electrical system. Solutions are also generally already known from the prior art in which the internal combustion engines continue to run during the maintenance work. A known solution comprises mechanically separating the driving internal combustion engine from the alternator. Another solution comprises short-circuiting and grounding the DC current lines. These solutions are, however, complex and/or expensive since they have to be carried out with a larger mechanical effort and using special electrical tools and trained personnel.